(a) Field of the Invention
The present invention relates to a display device and a driving method thereof, and more particularly, to a display device having a contact determiner.
(b) Description of the Related Art
Due to recent demands for reduction in the weight and thickness of personal computers and televisions, for example, a reduction in the weight and thickness of a display device is required. Thus, cathode ray tubes (“CRTs”) are now being replaced with flat panel display devices.
Examples of flat panel display devices include a liquid crystal display (“LCD”), a field emission display (“FED”) device, an organic light emitting device (“OLED”), and a plasma display panel (“PDP”) device.
Each of the active flat panel displays includes a plurality of pixels arranged in a matrix, and controls strength of light based on luminance information of each pixel to display images. LCDs among the active flat panel displays typically include a pair of panels that are provided with pixel electrodes and a common electrode, as well as a liquid crystal layer with dielectric anisotropy interposed between the two panels.
An LCD generates electric fields by applying voltages to pixel electrodes and a common electrode, and the strengths of the electric fields applied thereto are varied to adjust the transmittance of light passing through the liquid crystal layer, thereby displaying images.
A touch screen panel is an apparatus that writes or draws a character or a picture through contact with a finger, a pen, etc., on a screen. Touch screen panels may be used for a machine such as a computer to perform a desired command by executing a program when an icon is pressed. An LCD to which a touch screen panel is attached may have two primary functions: determining whether a contact occurs, and determining contact position information. However, the addition of a touch screen feature to the LCD comes with the addition of problems such as an increase in the cost of a display, yield decrease due to the addition of a manufacturing process for bonding a touch screen panel on a liquid crystal panel, luminance deterioration of the liquid crystal panel due to the passage of light through an additional layer, an increase in product thickness, and other related problems.
Therefore, technology for providing sensing units within pixels that display an image in an LCD instead of an additional touch screen panel has been developed. The sensing unit senses a variation of light or pressure applied to a screen of the LCD by a touch of a finger, etc. of a user, to determine whether there has been contact with the screen and a contact position.
The sensing units are connected to a plurality of bias voltages. Thus, when a contact occurs, the sensing unit corresponding to the contact position generates a sense data signal based on the bias voltage and outputs the sense data signal.
Since the sensing units are in response to a bias voltage variation, sense data signals from the sensing units are varied in accordance with the bias voltage variation. When impulse noises occur in the bias voltages, sense data signals are incorrectly generated due to the impulse noise.